The field of the present invention is a portable apparatus for performing tests to identify the blood group and blood type of a patient according to the ABO and Rh blood type classification systems, and methods of using such apparatus.
The testing procedures for determining the ABO blood group and Rh type of an individual's blood are well known to those skilled in the art. The major blood groups are: type A, type B, type A,B and type O. These blood groups are determined by the antigens present on an individual's red blood cells. An individual with type A blood carries red blood cells with type A antigens. In addition, persons of a particular ABO type have antibodies in their blood plasma which react with the antigens that they lack. For example, individuals who are type A have antibodies to the B antigen. Type O individuals have both anti-A and anti-B antibodies. Typically blood typing involves both "forward" and "reverse" typing. Forward typing tests are performed on the person's red blood cells to determine which antigens are present. A confirmatory, reverse typing test to determine which antibodies are present is also usually performed in the laboratory on the individual's blood serum or plasma. (Technical Manual of the American Association of Blood Banks, 8th Ed. 1981, Washington, D.C.).
An additional important antigen is the Rho(D) antigen (hereinafter referred to as the Rh antigen). Determination of the presence or absence of the Rh antigen is known as determining the Rh type of a patient's blood. The presence or absence of the Rh antigen has significance during pregnancy. If a pregnant woman has Rh negative type blood, she may have developed Rh antibodies in a prior pregnancy. If her fetus has Rh positive type blood the mother could transfer Rh antibodies to the fetus, resulting in its death.
It is imperative in administering blood transfusions that the donor's blood have the same red blood cell antigens as those of the recipient patient, to prevent complications from introduction of incompatible blood. The introduction of incompatible blood into a recipient who has circulating antibodies may result in rapid destruction of the transfused red blood cells by the recipient's antibodies. This is known as actue hemolytic transfusion reaction. Acute hemolytic transfusion reactions are among the most feared of such blood transfusion complications. Such reactions may result in actue renal failure and may end in death. (Fatalities From Blood Transfusion, Byron A. Nyhre, JAMA, Vol. 224 No. 12, Pg. 1333, 1980). Most ABO incompatibility deaths involve blood group O recipients since they have the least number of possible compatible donors. (Schmidt, Immunobiology Of The Erythrocyte, Allan R. Liss, 1980, The Mortality From Incompatible Transfusion, pgs. 251-261, 1980.)
Acute hemolytic transfusion reactions account for the majority of deaths reported to the Food and Drug Administration each year by FDA-Registered Transfusion Services. Between the years 1976 and 1978, 22 deaths were reported to the FDA as a result of transfusion and were attributable to ABO blood group incompatibility which resulted in acute hemolytic transfusion reactions. Of these 22 deaths, the majority of these were because the wrong patient was transfused. (Schmidt, supra and Myhre, supra). In particular, a major cause of the transfusion of incompatible blood is clerical error. Clerical errors can occur at any point from the time of drawing a patient's blood, through the classification of that person's blood type. Such errors can also occur at the point where donor blood is transfused to that patient. Transfusions may occur at numerous locations in the hospital removed from the testing laboratory including the patient's bedside, operating room or the emergency room of the hospital. Clerical errors include mislabeling of the blood sample taken from the patient, drawing blood from the wrong patient, or transferring the wrong unit of blood to a patient.
The usual blood typing procedures are performed in a laboratory and test an individual's blood cells for the presence of the various antigens. Typically, a patient's blood sample is mixed together with a blood typing reagent. The mixture is then examined visually for an agglutination reaction. The blood typing reagents that are used in most typing tests to determine ABO blood group are anti-A, anti-B, and anti-A,B. The reagents used for Rh typing are anti-Rho (D) and an Rh control solution. These laboratory testing procedures require numerous devices and procedures including centrifugation, pipetting, and mixing of reagents in various containers. Typically several blood samples from different patients are run in blood testing apparatus simultaneously. It is obvious that clerical error that can lead to incorrent identification or interchanging of a blood sample can occur at any one of the many steps used in typing the blood in the laboratory setting.
There is available in the prior art individual plastic containers into which individual microtubes carrying a blood sample may be inserted. These containers hold a saline solution to dilute the blood sample. The containers are almost entirely made of soft plastic and are compressed by manual pressure to draw the blood into the container. The diluted blood sample is then transferred to an appropriate location, such as the laboratory, for blood counting. No blood typing reactions are carried out within such containers. There is also available in the prior art pre-packaged reagents within centrifugation apparatus for blood testing in a laboratory (U.S. Pat. Nos. 3,713,775 and 3,707,354) and predispensed reagents in separate containers for progressive mixing of the reagents with a single sample in a central chamber (U.S. Reissue Pat. No. Re. 29,725).
Presently, it is possible, to determine the ABO group of a patient's blood in a location other than a laboratory, for example a hospital bedroom, using individual testing materials. A drop of typing reagent, and a drop of the blood sample are placed on a glass slide. The reagent and blood sample are mixed together on the slide and the mixtures observed by the technician for agglutination. The disadvantages of this method are obvious; the procedure is inconvenient and tedious and can result in incorrect identification of the ABO blood group.
Additionally, a disadvantage of the techniques and apparatus for blood typing in the prior art is that a physician cannot perform an initial determination of a patient's ABO blood group and Rh blood type in his/her office because of the equipment and procedures required for laboratory blood testing. There is presently no easy and reliable means or method available for carrying out blood typing tests at any location removed from a laboratory.